Frictionless zero spring rate seal



June 1964 w. w. BLASE ETAL 3,137,309

FRICTIONLESS ZERO SPRING RATE SEAL Filed April 30, 1962 4 Sheets-Sheet lFIG. ft

ATTORNEY June 16, 1964 w. w. BLASE ETAL 3,137,309

FR'ICTIONLESS ZERO SPRING RATE SEAL Filed April 30, 1962 4 Sheets-Sheet3 ATTORN EY June 16, 1964 w. w. BLASE ETAL 3,137,309

FRICTIONLESS ZERO SPRING RATE SEAL Filed April 30, 1962 4 Sheets-Sheet 4INVENTOR E a gm F 6 6 ATTORNEY stitute different biasing springs.

allow'sjcontinuous spring rate adjustment without substi- York FiledApr. 30, 1962, Ser. No. 190,888 a 16 Claims. (Cl. 137-83) This inventionrelates to pressure seals, and more particularly, to devices for sealinghydraulic or pneumatic fluid pressures withina movable device which mustbe capable of limited motion with minimum friction and minimum opposingspring forces. In the automatic con trol arts, various types ofhydraulic and pneumatic amplifying and regulating apparatus utilize thepositions of such movable devices to control the operation and determinethe output from the apparatus. For example, in the Well known jet piperegulator, an input signal force or displacement is used to determinethe position of a rotary jet pipe with respect to two receiving portsand thereby proportion receipt of fluid being expelled at high pressurefroni'the jet pipe between the two receiver ports, thereby providing apressure difference between the two ports. The pressure difference,which usually is far greater than the force required to position the jetpipe, may be used to control a valve or other load, with a feedbackconnection commonly made from the load to the jet pipe. In order to makesuch a hydraulic amplifier sensitive to very small or weak inputsignals, it is necessary that the jet pipe be mounted to rotate or pivotwith minimum static friction and minimum moving friction. In order toconnect a stationary, highpressure fluid source to such a pivotable jetpipe and still allow the jet pipe to pivot with minimum friction, theuse of sealed fiexure pivots has manyadvantages over packing boxes andother high-friction types of high pressure seals, as explained in detailin U.S. Patent No. 2,724,397 issued November 22, 1955 to HerbertZiebolz. While such use of flexure-type connections may be used toprovide substantially frictionless and totally sealed connectionsbetween a stationary high pressure source and a movable jet pipe, theopposing spring forces applied to the jet pipe by such flexure-typeseals are frequently considerable in magnitude, making the jet pipeamplifier response undesirably insensitive to weak input signals.Ideally such flexure pivot seals should offer no resistance to jet pipemovement. The invention provides means for compensating or cancellingout the flexure connection spring forces, so that only greatly reducedor insignificant spring forces oppose the input error signals applied tothe jet pipe, thereby making the jetpipe amplifier much more sensitiveto small error signals.

In such jet pipe amplifier systems, adjustable biasing springs arefrequently utilized to determine the position system gain factors, itusually hasbeen necessaryto sub- The invention not only tution ofbiasing springs, but even allows such springs to be eliminated whilestill providing continuously adjustable system gain. I

Briefly described, the invention contemplates the use of bi-directionalmagnet means which provides magnetic forces to oppose the spring forcesapplied to the jet pipe by the flexure-type high pressure sealconnections. Thus it is a primary object of the present invention toprovide an improved high pressure seal connection between a stationarymember and a movable member, so that friction United States Patent O3,131,309 Patented June 16 1964 and spring forces do not oppose motionof the movable member.

It is a more specific object of the invention to provide magnetic meansfor compensating or cancelling spring forces which resist motion-of amember which is connected by a flexure-type high pressure seal to bemovable bidirectionally with respect to a stationary member.

It is an additional object of the invention to provide a jet pipeamplifier assembly having improved set point adjusting means, the springrate of which may be adjusted continuously in a simple and accuratemanner.

' Other objects of the invention will in part be obvious and will inpart appear hereinafter. f

The invention accordingly comprises the features of construction,combinations of elements, and arrangement of parts, which will beexemplified in the constructions hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the inventionreference should be had to the following detailed description taken inconnection with the accompanying drawings, in which:

FIGS. 1a and 1b are a pair of orthogonally-related views illustratingone simple form of the invention, with certain parts cut away for easeof illustration;

FIGS. 2a and 2b. are a similar pair of views illustrating a modifiedform of the invention;

' FIG. 3 is a section view of a further embodiment of the invention;

FIG.4 is a graph useful in tion of the invention; and p a 7 FIGS. 5 and5b are modified embodiments of theinvention which utilizeelectromagnetic bi-directional spring-rate compensating means.

FIGS. 6a, 6b and 6c are a trio of orthogonal views illustrating anexemplary magnet positioning arrangement useful in many embodiments ofthe invention.

In FIGS. 1a and 1b jet pipe 10 is shown supported by atransversely-connected hollow torque tube 12 which is fixedly mounted tothe stationary body 20 of the jet pipe assembly at each of ends 13, 14of torque tube 12, with ends 13, 14 sealed to body 20 and non-rotatablewith respect to body 20. Input signal forces are applied by means shownas comprising a pressure-operated expansible bellows 9, one end of whichis fixedly attached understanding the operato jet pipe 10 and the otherend of which is fixedly atrequired in such prior art systems to providedifferent v tached to housing 20. Threaded passage 8 allows a pressureto be sensed to be connected to the interior of bellows 9, so thatvariation of the pressure applied to bellows 8 operates to extend orretract bellows 9, thereby operating to rotate jet pipe 10 about axisx-x. Fluid from a high pressure source (not shown) is connected throughpassage 16 to flow through hollow tube 12, through an opening 17 in tube12 into jet pipe 10, and then out through nozzle end 18 of jet pipe 10.If desired, a passageway similarto 16 may be provided to end '13 of tube12 to supply the high pressure fluid to both ends of the tube. Tube 12,being rigidly attached to body 20 at its ends, applies an opposingtorque to jet pipe 10 which tends to center jet pipe 10 in a free centerposition, and in assembly of the unit, the ends of tube 12 are fastenedwith nozzle'18 centered with respect to ports 21, 22, so that in theabsence of any applied external force the jet pipe 10 will be centeredbetween the ports. Sometimes it is desired to bias the jet pipe to adifferent zero position. In order to adjust the jet pipe zero position,and thereby determine the set point of the system in which the jet pipeamplifier is used, it is common to provide springs which may be adjustedto provide different set points. Frequently it isdesirable to be able toadjust the spring rate of set point biasing springs, and the most commonway of providing such adjustment in the prior art has been to substitutedifferent springs having different spring constants. The inventionallows adjustment of both the set point and the spring rate without thenecessity of changing springs, and in many applications of the inventionallows such springs to be omitted altogether. Irrespective of thedirection in which jet pipe 19 is deflected, it will be seen that tube12 will provide a torsional restoring force in a direction tending tocenter the jet pipe. The invention serves to decrease or substantiallyeliminate that restoring force.

Fluid expelled at high velocity from nozzle 18 of jet pipe is directedtoward and enters receiver ports 21, 22, which are connected by meansshown schematically as comprising conduits 23, 24 to opposite ends of ahydraulic motive means shown as comprising cylinder 34 and piston 31. Ifjet pipe 10 is directed so as to discharge fluid equally to ports 21 and22, equal pressure will exist on opposite sides of piston 31 and thepiston will remain stationary. If jet pipe M9 is rotated or pivoted veryslightly about axis x-x, however, the decrease of pressure on one sideof piston 31 and simultaneous increase of pressure on the other sidewill immediately tend to translate piston 31, and an external loadattached to piston rod 32. In a typical application of the invention,the load, such as valve V, controls an operating condition of a processor a machine in a manner to affect the pressure applied to bellows 9, oralternatively, to derive a force or displacement signal which may beotherwise mechanically connected to jet pipe 1t Rigidly attached to jetpipe 10, preferably on the end of jet pipe 10 opposite from nozzle 18 isa magnetic armature element 40, formed of soft iron, for example. As jetpipe 10 is rotated about axis xx, armature ele ment 40 is translatedbetween a pair of magnetic forceproducing means shown as comprising apair of similar, but oppositely disposed permanent magnets 4-2, 44 whichare rigidly though adjustably mounted 'to the jet pipe amplifier body 20by means shown as comprising adjusting screws 47, 48 to the ends ofwhich magnets 4-2, 44 are rotatably attached. Considering only theforces applied to jet pipe 10 by magnets 42 and 44, it will be seen thatthe central or zero position of jet pipe 10, that position shown in FIG.1a, is a position of unstable equilibrium, since magnets 42 and 44 exertequal and opposite attractive forces on armature 40, thereby providingno net rotational moment on jet pipe 10. As jet pipe 10 is rotated aboutthe xx axis, however, armature 40 will be seen to move'nearer one of themagnets and farther away from the other of the magnets, increasing theattractive force applied by the magnet the armature approaches, anddecreasing the attractive force applied by the other magnet. Thus itwill be seen that deflection of jet pipe 10 in a given direction resultsin a restoring force from the torque tube tending to re-center the jetpipe but also an. oppositely-acting magnetic force tending to furtherdeflect the jet pipe away from its center position. By selection of thestrength and spacing of the magnets, one may cause the magnetic forcessubstantially to cancel out the spring forces of torsion tube, so thatthe jet pipe can be swung not only frictionlessly but substantiallywithout spring restraint over its required range of deflection in eitherdirection. Adjustable stops 31, 32 serve to limit rotation of jet pipe10 to within the-operating range of bellows 9 and so that some of thefluid being expelled from the jet pipe always enters one or the other ofports 21, 22. Stops 31, 32 by limiting rotating of jet pipe 10, alsolimit the travel of armature 40 in the air gap between magnets 42, 44,for a purpose to be explained below in connection with FIG. 4.

FIGS. 2a and 2b illustrate a modified form of the invention in which aT-shaped jet pipe 10 is provided with a rigid, hollow, transverse uppercross member forming a pair of coaxial left and right mounting arms 10aand 10b, one of which (10a) is rotatably mounted in guide bearing 13'carried in body 20, and the other of which is fixedly attached at. 19 toone end of a coaxial torque tube 12, the other end of torque tube 12being fixedly attached to body 20 at 25. Jet pipe 10 will be seen to beconnected to the stationary housing through arm 10b and tube 12, so thatthe spring rate governing rotation of the jet pipe is that of tubes 10])and 12 in series, resulting in a lower spring rate than if tube 1012were attached directly to the housing, and avoiding the use of a longsingle torsion tube, which would tend to bend and improperly positionthe jet pipe nozzle with respect to the receiver ports. A further guidebearing 26 serves to align arm 1% of the jet pipe with torque tube 12,thereby to prevent rotation of the jet pipe about any axis other thanaxis xx. The input signal force or displacement may be connected at hole27' to rigid lever arm 27 extending from jet pipe 1%), or alternatively,end 10a of jet pipe it? may protrude through body 20 as shown at 28 toreceive a rotary input torque or angle signal. As in FIGS. la and lb,the magnetic'compensating means comprises an armature 40 of magneticmaterial disposed between a pair of permanent magnets 42, 44, only oneof which is shown in FIG. 2a. Non-magnetic bar 47 extends across thebody of the apparatus to abut magnets 42, 44 and thereby preventrotation of the magnets as they are translated inwardly or outwardly byrotation of their respective adjusting screws. In view of thedescription of the operation of the device of FIGS. 1a and 1b, operationof the device of FIGS. 2a and 2b should be apparent without furtherexplanation.

FIG. 3 illustrates a further embodiment of the invention in which jetpipe 10 is rigidly connected to lever arm 27', one end of which isprovided with a magnetic force element 51' such as a magnet or a magnetwinding which cooperates with a stationary force-producing magnetic coil52, so that energization of winding 52 and/or member 51 serves to applya force to arm 27, and thereby rotate jet pipe in. If magnetic forceelement 51 comprises an armature of unmagnetized magnetic material, theforce applied to arm 27, which is always an attractive force, varies indirect proportion to the current through coil 52. In devices whereelement 51 is a permanently magnetized core, the force variesproportionally to the current through coil 52 but the force may beeither attractive or repulsive. In devices where element 51 is a coilelectrically connected in series with coil 52, the force varies inaccordance with the square of the current through the coils, and theforce may be either attractive or repulsive. Arm 27' and jet pipe 10 arepivotally mounted by means of fiexure pivot 53 which comprises twomutually perpendicular flexible strips 53a, 53b, one end of each stripbeing affixed to jet pipe 10 and arm 27, and the other end of each stripbeing fastened to the stationary body of the jet pipe amplifierassembly. As will be clear from FIG. 3, forces produced by currents inassembly 51, 52 will tend to rotate jet pipe 10 and arm 27 about an axisperpendicular to the plane of the paper in FIG. 3 and passing throughpoint A,'the intersection of fiexure strips 52a, 5312. It will be seenthat the rotational force applied to jet pipe 10 by assembly 51, 52 willbe opposed by the opposing spring force of flexure pivot 53, by anyspring force which may be developed by flexible supply hose 54 as thejet pipe rotates, and by any spring force which flexing of electricalconductors 56, 56 may cause if member 51 comprises a winding. Magnets42, 44 acting on magnetic armature 46, which is rigidly attached to arm27, are positioned to apply forces substantially equal to the resultantof the three mentioned opposing forces, so that the net force applied tojet pipe 10 is substantially only that provided by assembly 51, 5'2.

In the case of a simple pulling magnet in which the permeability andarea of the magnetic circuit do not change, the force applied by themagnet to an object is inversely proportional to the square of thedistance between the magnet and the object. FIG. 4 illustrates the forceversus displacement characteristics of magnets 42 and 44 by means ofcurves #1 and #2, respectively, while curve #3, which is the algebraicsum of curves #1 and #2, illustrates the net force acting on thearmature situated between the two magnets. It will be seen that the netforce becomes quite'non-linear at large deviations or displacements fromthe centered or zero displacement position, but that a fairly linearregion exists near center position. Because flexure bearings and theother spring restraintson a jet pipe are not operated beyond theirelastic limits, the forces they generate are substantially linear, andtherefore in practicing the invention, only the linear. position of thenet force curve is utilized, by providing magnets of sufficient strengthto providesufiicient compensating force with motion limited to typicallyabout of the air gap between the magnets. The effect of adjustment ofthe air gap may be seen readily from FIG. 4. Decreasing the spacingbetween the magnets amounts to shifting curve #1 rightwardly and curve#2 leftwardly, and increasing the spacing between the magnets has, ofcourse, opposite effects. The magnets may be shifted together, eitherrighti wardly or leftwardly, to adjust the zero signal input position ofthe jet pipe relative to the receiver ports, and thereby adjust thesystem set point. The magnets may be spread apart to provide the sameeffect upon biasing spring spring rate as has been accomplishedheretofore by substitution of a weaker spring, andvice versa. It will beseen that since system set point can be determined by shifting themagnetic means as a pair, that the set pointbiasing springs heretoforeused in many jet pipe regulator systems may be eliminated, and whetheror not such springs are used, adjustment of the air gap between themagnets may be used to adjust system spring rate, in a continuous sense.

As well as using permanent magnets, it is within th scope of theinvention to utilize electromagnets to provide opposing spring forcesapplied to jet pipes. As shown in FIG. 5a, magnet cores, 42a and 44a arefixedly mounted to body on a non-magnetic plate 57 and provided withwindings 42b and 44b, respectively. Each winding is connected through acurrent controlling means shown as comprising a rheostat (59, 60) to acurrent source (not shown) connected to terminals 71, 72. By adjustmentof rheostats 59 and 60 the currents through the electromagnet windingsmay be adjusted, so that the electromagnets of FIG. 5a need not bephysically moved to effect adjustment. As shown in FIG. 5b, theelectromagnets also may be connected in a bridge circuit withpotentiometer 78 to proportion the flow of current between the twoelectromagnets, thereby to adjust the bal ance point of the magneticmeans, and additional means such as rheostat 79 may be used to controlthe current through and the strength of, both electromagnets.

FIGS. 6a, 6b and 6c are plan, elevationand section views, respectively,showing a preferred magnet mounting and adjustment arrangement which maybe used in positioning the invention.

In FIGS. 6a, 6b and 6cthe magnet mounting and adjusting assembly will beseen to include a pair of stationary end plates 61, 62 which are fixedlymounted to stationary body 20 of the jet pipe amplifier, with a pair ofparallel rods 63, 64 extending between plates 61, 62 to provide a guidetrack fora pair of traveling nut members 65, 66. Magnets 42, 44 arefixedly attached, as by means of a suitable cement, to traveling nutmembers 65, 66 respectively. A rotatable and axially slidable shaft 67which slidably passes through block 61 is provided withoppositely-threaded portions 67a and 67b, and the right end of shaft 67butts against pin 68, which is threaded through block 62 and locked inplace by jam nut 69. A slot in the end of threaded pin 68 allows axialadjustment of pin 68 by means of a screwdriver. Spring means 70 urgestraveling nut member 65, axially slidable shaft 67 and traveling nutmember rightwardly, holding the end of shaft 67 against pin 68. As pin68 is rotatably adjusted, it will be seen that magnets 42 and 44 will bemoved together, thereby allowing adjustment of the set point of theapparatus. Because portions 67a and 67b are oppositely threaded, it willbe seen that rotation of shaft 67 in one direction will operate todecrease the spacing between the magnets, while rotation in the oppositedirection will serve to increase the spacing, thereby allowingadjustment of the system gain.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained, andsince certain changes may be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

Having described our invention, what we claim as new and desire tosecure by Letters Patent is:

,1. A jet-pipe hydraulic amplifier, comprising, in combination: a bodydefining an enclosed cavity and having a pair of receiver ports spacedin a wall thereof; a jet pipe connected to a fluid pressure source andadapted to expel fluid toward said receiver ports, said jetpipe beingmounted within said cavity and pivotally attached to said body byflexible suspension means; means for applying an input signal force tosaid jet pipe tending to pivot said jet pipe against restraining forcesdeveloped by said suspension means; an armature of magnetic materialrigidly attached to said jet pipe; and a pair of mutually opposingmagnetic means spaced on opposite sides of said armature to applyopposing forces to said armature to tend to rotate said jet pipe from areference position of unstable equilibrium produced byapplication ofsaid opposing forces to said jet pipe by said magnetic means.

2. Apparatus according to claim 1 in which said jet pipe comprises aT-shaped hollow tube having coaxial left and right arms and a third armperpendicular thereto, one of said coaxial arms being rotatablejournalled in said body, the second of said coaxial arms being connectedto said body through a hollow torque tube, said third arm extending fromthe junction of said left and right arms and terminating in a nozzle.

3. Apparatus according to claim 2 in which said hollow torque tube isdisposed coaxially withsaid left and right arms, and in which saidapparatus includes rotary hearing means disposed between said torquetube and said second of said coaxial arms.

4. A jet-pipe hydraulic amplifier, comprising, in combination: astationary body defining an enclosed cavity and having a pair ofreceiver ports spaced in a wall thereof; a pivotable jet pipe connectedto a fluid pressure source and adapted to expel fluid toward saidreceiver ports, thereby to proportion the flow of fluid to therespective ports as said jet pipe is pivoted, said jet pipe beingmounted within said cavity and pivotally attached to said body by meansof a flexible suspension means adapted to resiliently oppose pivotalmovement of said jet pipe away from a reference position; an armature ofmagnetic material rigidly attached to said jet pipe; and'a pair ofmagnetic means spaced on opposite sides of said armature to apply forcesto said armature to oppose the forces applied to said jet pipe by saidflexible suspension means.

.5. Apparatus according to claim 4 in which each of said magnetic meanscomprises an electromagnet connected through a variable resistance to asource of electrical current.

6. Apparatus according to claim 5 in which said electromagnets areconnected through first and second respective variable resistances toallow independent adjustment of the currents through saidelectromagnets.

7. Apparatus according to claim 5 in which said electromagnets areconnected in a bridge circuit with a potentiometer operable toproportion the fiow of current between said electromagnets, and a secondvariable resistance connected to control the flow of current to saidbridge circuit.

8. Apparatus according to claim 1 in which said flexible suspensionmeans comprises a hollow tube having its ends fixedly attached to saidbody, in which said jet pipe extends perpendicularly from the side ofsaid tube, and in which said fiuid pressure source is connected to saidjet pipe through said hollow torque tube.

9. Apparatus according to claim 1 in which said jet pipe is pivotablethrough a limited distance and in which said magnets are spaced withrespect to said armature so that said armature traverses less than 20%of the distance between said magnets as said jet pipe is pivoted throughsaid limited distance.

10. Apparatus according to claim 1 having an actuating arm rigidlyattached to said jet pipe, and further magnetic means, electricallyconnected to an external circuit and mechanically connected to said jetpipe for applying an external signal force to said jet pipe.

11. Apparatus according to claim 4 in which said permanent magnets aresubstantially equal in magnetometive force and symmetrically disposed onopposite sides of said armature, with the poles of one magnet facingopposite polarity poles of the other magnet.

12. In a jet-pipe servomechanism system which includes apivotally-mounted jet pipe connected to a fluid pressure source andoperable to proportion the flow of fluid to a pair of receiver ports toprovide a differential pressure signal, expansible chamber motive meansoperated by said differential pressure signal to control a load andfeedback means responsive to operation of said motive means forrebalancing said jet pipe to a set point position; springratecompensating means, comprising, in combination: an armature of magneticmaterial rigidly attached to said jet pipe; a pair of mutually-opposingmagnetic means spaced on opposite sides of said armature to apply forcesto said armature; and means for varying the magnitudes of said forcesapplied to said armature to vary the loop gain of said servomechanismsystem.

13. Apparatus according to claim 4 including means for adjusting saidpair of magnetic means conjointly as a pair with respect to saidarmature.

14. Apparatus according to claim 4 including means for adjusting saidpair of magnetic means mutually oppositely with respect to saidarmature.

15. Apparatus according to claim 4 including first means for moving saidmagnetic means in the same direction to adjust the midpoint between saidmagnetic means Without altering the distance between said magneticmeans, and second means for moving said magnetic means in mutuallyopposite directions to adjust the distance between said magnetic meanswithout altering the position of the midpoint between said magneticmeans.

16. In a jet-pipe servomechanism system having a pivotally-mounted jetpipe connected to a fluid pressure source and operable to proportion theflow of fluid to a pair of receiver ports to provide a differentialpressure signal, expansible chamber motive means operated by saiddifferential pressure signal to control a load, and feedback meansresponsive to operation of said motive means for rebalancing said jetpipe to a set point position; springrate compensating means, comprising,in combination: an armature of magnetic material rigidly attached tosaid jet pipe; a pair of mutually-opposing magnetic means spaced onopposite sides of said armature to apply opposing forces to saidarmature; and means for varying the position between said magnetic meansat which said forces applied to said armature cancel each other, therebyto vary said set point position of said servomechanism system.

References Cited in the file of this patent UNITED STATES PATENTS1,620,707 Wunsch Mar. 15, 1927 2,601,207 Jacques June 17, 1952 2,699,356Ziebolz Jan. 11, 1955 2,724,397 Ziebolz Nov. 22, 1955 2,990,839 Ray July4, 1961 3,011,505 Reip Dec. 5, 1961 3,078,863 Wolpin et al Feb. 26, 1963

1. A JET-PIPE HYDRAULIC AMPLIFIER, COMPRISING, IN COMBINATION: A BODYDEFINING AN ENCLOSED CAVITY AND HAVING A PAIR OF RECEIVER PORTS SPACEDIN A WALL THEREOF; A JET PIPE CONNECTED TO A FLUID PRESSURE SOURCE ANDADAPTED TO EXPEL FLUID TOWARD SAID RECEIVER PORTS, SAID JET PIPE BEINGMOUNTED WITHIN SAID CAVITY AND PIVOTALLY ATTACHED TO SAID BODY BYFLEXIBLE SUSPENSION MEANS; MEANS FOR APPLYING AN INPUT SIGNAL FORCE TOSAID JET PIPE TENDING TO PIVOT SAID JET PIPE AGAINST RESTRAINING FORCESDEVELOPED BY SAID SUSPENSION MEANS; AN ARMATURE OF MAGNETIC MATERIALRIGIDLY ATTACHED TO SAID JET PIPE; AND A PAIR OF MUTUALLY OPPOSINGMAGNETIC MEANS SPACED ON OPPOSITE SIDES OF SAID ARMATURE TO APPLYOPPOSING FORCES TO SAID ARMATURE TO TEND TO ROTATE SAID JET PIPE FROM AREFERENCE POSITION OF UNSTABLE EQUILIBRIUM PRODUCED BY APPLICATION OFSAID OPPOSING FORCES TO SAID JET PIPE BY SAID MAGNETIC MEANS.